24-表油菜素内酯调控活性氧代谢增强杏果实采后抗病性

24-Epibrassinolide Regulates Active Oxygen Metabolism to Enhance Postharvest Disease Resistance of Apricot Fruit

为研究24-表油菜素内酯(24-epibrassinolide,EBR)处理对杏果实采后黑斑病发生及活性氧代谢的影响,以’赛买提’杏果实为实验材料,用0.9 mg/L EBR对杏果实进行减压渗透处理,自然晾干后置于温度(1.0±0.5)℃、相对湿度90%~95%的条件下贮藏48 h,接种链格孢菌(Alternaria alternata)后于相同条件贮藏,定期取样测定EBR处理对杏果实采后黑斑病与活性氧代谢的影响。结果表明:EBR处理可显著提高杏果实接种前期H2O2含量(P<0.05),显著提高杏果实接种贮藏期间超氧化物歧化酶、过氧化物酶和接种后期过氧化氢酶的活力(P<0.05),明显抑制超氧阴离子自由基(O2·^-)产生速率,有效降低丙二醛的含量、细胞膜渗透率和发病率的上升,显著抑制杏果实病斑直径的扩大。同时,透射电子显微镜结果显示,EBR处理能较好地维持杏果实线粒体、叶绿体等细胞器在贮藏过程中结构的完整性。说明EBR处理抑制杏果实采后黑斑病的发生与调控其活性氧代谢和维持其细胞器结构完整性密切相关。

In order to investigate the effect of 24-epibrassinolide(EBR)treatment on postharvest black spot and reactive oxygen metabolism of apricot.’Saimmaiti’apricot fruit were soaked with 0.9 mg/L EBR under reduced pressure or distilled water as a control,dried under natural sunlight,and then stored at(1.0±0.5)℃and relative humidity of 90%–95%for 48 hours.Afterwards,the fruit were inoculated with Alternaria alternata and then kept under the same conditions.Sampling was conducted periodically to examine the effect of EBR treatment on postharvest black spot and reactive oxygen metabolism.The results showed that EBR treatment significantly increased the content of hydrogen peroxide(H2O2)shortly after inoculation(P<0.05),continuously and significantly improved the activity of superoxide dismutase(SOD)and peroxidase(POD)over the entire culture period and significantly enhanced catalase(CAT)activity during the later stages(P<0.05).In addition,it significantly inhibited the production rate of superoxide anion radical(O2·^-),effectively reduced the content of malondialdehyde(MDA)as well as the increase in cell membrane permeability and the incidence of disease,and greatly inhibited the expansion of the lesion.Meanwhile,the results of transmission electron microscopy showed that EBR treatment could maintain the structural integrity of mitochondria,chloroplasts and other organelles in apricot fruit during storage.The mechanism behind the inhibition of the occurrence of postharvest black spot in apricots by EBR treatment may be closely related to regulating reactive oxygen metabolism and maintaining the structural integrity of organelles.